Django补充——中间件、请求的生命周期等

一：中间件

django 中的中间件（middleware），在django中，中间件其实就是一个类，在请求到来和结束后，django会根据自己的规则在合适的时机执行中间件中相应的方法。

在django项目的settings模块中，有一个 MIDDLEWARE_CLASSES 变量，其中每一个元素就是一个中间件，如下图。

与mange.py在同一目录下的文件夹 wupeiqi/middleware下的auth.py文件中的Authentication类

中间件中可以定义四个方法，分别是：

process_request(self,request)
process_view(self, request, callback, callback_args, callback_kwargs)
process_template_response(self,request,response)
process_exception(self, request, exception)
process_response(self, request, response)

以上方法的返回值可以是None和HttpResonse对象，如果是None，则继续按照django定义的规则向下执行，如果是HttpResonse对象，则直接将该对象返回给用户。

Django补充——中间件、请求的生命周期等

自定义中间件：

1、创建中间件类

class RequestExeute(object):
      
    def process_request(self,request):
        pass
    def process_view(self, request, callback, callback_args, callback_kwargs):
        i =1
        pass
    def process_exception(self, request, exception):
        pass
      
    def process_response(self, request, response):
        return response

"""
class M1(MiddlewareMixin):

    def process_request(self,request):
        print('m1.process_request')

    def process_view(self,request, view_func, view_func_args, view_func_kwargs):
        print('m1.process_view')

    def process_exception(self,request,exception):
        print('m1.process_exception')

    def process_response(self,request,response):
        print('m1.process_response')
        return response

    def process_template_response(self,request,response):
        print('m1.process_template_response')
        return response

class M2(MiddlewareMixin):
    def process_request(self, request):
        print('m2.process_request')

    def process_view(self, request, view_func, view_func_args, view_func_kwargs):
        print('M2.process_view')

    def process_exception(self,request,exception):
        print('m2.process_exception')
        return HttpResponse('开发的程序员已经被打死')
    def process_response(self, request, response):
        print('m2.process_response')
        return response

    def process_template_response(self,request,response):
        print('m2.process_template_response')
        return response
"""
from django.shortcuts import HttpResponse,redirect
class MiddlewareMixin(object):
    def __init__(self, get_response=None):
        self.get_response = get_response
        super(MiddlewareMixin, self).__init__()

    def __call__(self, request):
        response = None
        if hasattr(self, 'process_request'):
            response = self.process_request(request)
        if not response:
            response = self.get_response(request)
        if hasattr(self, 'process_response'):
            response = self.process_response(request, response)
        return response

class M1(MiddlewareMixin):

    def process_response(self, request, response):
        print('m2.process_response')
        return response


class M2(MiddlewareMixin):
    def process_request(self, request):
        print('m2.process_request')

两种方式